How to use class from different project

Question

IDE: VS 2010, C# .net,

I have two win projects in 1 solution,

ProjA, and ProjB

now ProjA contains classA.cs

namespace ProjA
{
    class ClassA
    {
        public static int aValue = 5;
    }
}

same way ProjB contains ClassB.cs

namespace ProjB
{
    public class ClassB
    {
        public static int bValue = 10;  
    }
}

and here is FormA.cs

using System;
using System.Windows.Forms;
using ProjB;

namespace ProjA
{
    public partial class FormA : Form
    {
        public FormA()
        {
            InitializeComponent();
        }

        private void FormA_Load(object sender, EventArgs e)
        {
            int va = ProjB.ClassB.bValue;; //Here getting error.???
        }
    }
}

Error : Cannot resolve symbol ProjB

Hint: This Problem Is related to namespace, I am trying to access ClassB which is in ProjB from FormA which is in ProjA, Here ProjA and ProjB are the 2 winforms project in Same solution

---xxxx----------- THis problem has been solved.

but now I want to access ClassA.cs in FormB.cs (just reverse of above problem),

when I tried same way ProjB(RighClick) -> Add reference -> ProjName(Tab) ProjA(Click)

The new problem I am facing is its saying unable to add it will create circular dependency, Please suggest How to solve this issue.

I want to access ClassA.cs in ProjB->FormB.cs here FormB is in ProjB

Yes I have added you can see in 3rd block of code in post using ProjB — yogeshkmrsoni, May 05 '14 at 10:02
possible duplicate of [How can I refer to a project from another one in c#?](http://stackoverflow.com/questions/2306652/how-can-i-refer-to-a-project-from-another-one-in-c) — Alexander R, May 05 '14 at 10:05
Create 3rd project where you will move your shared code for ProjA and ProjB and refer that project to both ProjA and ProjB. — Janne Matikainen, May 05 '14 at 11:33

Christian Cederquist · Answer 1 · 2014-05-05T10:07:15.177

0

ProjB is the namespace, so it doesn't know which class to use. If they're in the same solution(package of projects), just use the classname ClassB.(Or ProjB.ClassB.bValue)

If your projects aren't in the same Solution, go to Project A, File->Add->Existing Project, and add ProjB.

edited May 05 '14 at 10:07

answered May 05 '14 at 09:55

Christian Cederquist

513
3
16

What happens if you use ProjB.ClassB.bValue? – Christian Cederquist May 05 '14 at 09:59

score 0 · Answer 2 · answered May 05 '14 at 09:55

0

You need to create new instance of class or make it static. So this:

 namespace ProjB
{
public static class ClassB
{
  public static int bValue = 10;  
}

and then

int va = ClassB.bValue;

OR

int va = new ClassB().bValue;

answered May 05 '14 at 09:55

Matas Vaitkevicius

58,075
31
238
265

@user3593678 make classB static. – Matas Vaitkevicius May 05 '14 at 09:59

apomene · Answer 3 · 2014-05-05T10:08:00.277

0

Provided you have referenced correctly ProjB you just need to instatinate classB in ProjA:

using System;
    using System.Windows.Forms;
    using ProjB;

    namespace ProjA
    {
         ProjB.ClassB classb=new ProjB.ClassB();
        public FormA()
        {
            InitializeComponent();
            ....
           classb.bValue=....//set desired valued
        }

        private void FormA_Load(object sender, EventArgs e)
        {

            int va =classb.bValue;
        }

edited May 05 '14 at 10:08

answered May 05 '14 at 09:58

apomene

14,282
9
46
72

I updated the question, ClassB is not accessable because It is in ProjB and FormA is in projA – yogeshkmrsoni May 05 '14 at 09:59

score 0 · Answer 4 · answered May 05 '14 at 10:12

0

The problem was with reference,

I added reference

Right click ProjA -> References -> Add Reference, then I added ProjB.

And Problem resolved. :-)

answered May 05 '14 at 10:12

yogeshkmrsoni

315
7
21

sihirbazzz · Answer 5 · 2014-05-05T11:02:26.157

In your visual studio

1-) Right click to your solution

2-) Then open Properties of the solution..

In the properties page, on the left you'll see menus..

3-) Click to Project Dependencies

In Details of project Dependencies (right side of the page )

4-) Select your Project A from the DropDownList which has a label with "Project"

5-) Under the DropDownList Check (Mark as checked) the ProjectB

6-) Click to save / ok

This operation what you did, warns the compiler as so :

"When you start to build ProjectA, Before build/compile ProjectA First build/Compile ProjectB and then continue to build ProjectA"

or in another saying " Dear Compiler ! When you work with my ProjectA, You will need My ProjectB to do your work properly. So please also check my ProjectB.

Best Regards, Your Lovely Developer "

NOTE : Never circular reference (ProjectA depends to ProjectB and ProjectB depends to ProjectA) to eachother..this gets infinitive recursion error of the compiling your code..!

Visual Representation of The VS2010-ProjectDependencies Box

How to use class from different project

5 Answers5